Photochemical reactivity of the triosmium cluster 1,1-Os3(CO)10(bpcd) in the presence of P(OEt)3 and X-ray crystal structure of HOs3(CO)7[P(OEt)3][μ-{PPh(C6H4)} C=C(PPh2)C(O)CH2C(O)]: Unexpected ortho metalation and cluster face capping by a diphosphine ligand

Photochemical activation of the bpcd-chelated cluster 1,1-Os3(CO)10(bpcd) (1) in the presence of P(OEt)3 furnishes the simple substitution product 1,1,2-Os3(CO)9[P(OEt)3](bpcd) (2) initially, followed by the formation of the hydride cluster HOs3(CO)7[P(OEt)3][μ-{PPh(C6H4)}C=C(PPh2)C(O)CH2C(O)] (3). Both new clusters were isolated and characterized in solution by IR and NMR (1H and 31P) spectroscopies, with the solid-state structure of cluster 3 determined by X-ray diffraction analysis. Cluster 3 crystallizes in the triclinic space group P−1, a=9.366(2) Å, b=14.182(4) Å, c=17.672(4) Å, α=87.787(4)°, β=78.488(4)°, γ=71.785(4)°, V=2184.1(9) Å3, Z=2, Dcacl=2.123 Mg/m3; R=0.0488, Rw=0.1059 for 8527 observed reflections with I > 2σ(I). The presence of the seven-electron ligand μ-P{Ph(C6H4)}C=C(PPh2)C(O)CH2C(O) that caps one of the triangular faces in 3 through both phosphine moieties, the π bond of the dione ring, and an ortho-metalated aryl ligand is established.